Okay, what is the easiest way to check for a bad injector? I put a fuel pressure gauge on my car and at WOT it was good (42-43), but 5min. after i turn my car off it's already at 0. I believe this is causing my car to idle wierd. At idle, My car drops RPM from 1000 to 500 and occasionaly stalling, but this is with A/C on. When A/C is off, problem seems to bee pretty much gone, rpm bounce +/- 100. What can cause this, I had car scanned and nothing came up.

 

When I had a leaky injector on my RX7, the oil had a bluish tint to it and it REEKED of gas. If this helps, great, if not...that is about the only experience I have with fuel pressure.

I do have a mechanical gauge on the fuel rail and an electric fuel pressure gauge inside the car, so I will see how long mine takes to 0psi out when I drive it later today.

 

if you don't have fuel in your oil pan , it sounds more like your fuel pump is losing its prime. Is your car hard to start sometimes? I mean do you have to turn it over a few times before it cranks up?

 

Immediate loss of pressure on shutdown could be leaking injectors (pull the fuel rails up, turn the key on to pressurize the system, and look for drips), a faulty fuel pressure regulator (pull the vacuum line off the fuel pressure regulator and look/smell for gasoline in the line), or a failing check valve in the fuel pump. It shouldn't be causing erratic idle, unless the fuel pressure is unstable while the engine is running. Have you looked to see how steady the fuel pressure is at idle?

In addition to leaks, your injectors could be dirty, or you may have electrical problems (which would set a code).

 

Okay, Fuel pump has less than 1k on it. I have a gauge hooked up and when my idle drops downto 500, my fuel pressure drops as well. I have already pulled vacuum off Regulator, No leaking Gas. This problem is pretty much only occurs when the A/C is on at idle. When i have a/c off, it seems to be fine. But my main concern is losing fuel pressure so quick. How would i test for a failing check valve?

 

Car fires right up everytime with no hesitations

 

When the idle slows down, what happens to the voltmeter..... does the needle drop into the red? Sounds like you have a weak charging system, or excessive voltage loss in the wiring. Did you install a larger than stock pump? Did you get the optional wiring upgrade?

How far does the fuel pressure drop when the idle drops to 500rpm?

The hardest leak to pin down is the fuel pump check valve. You could try pinching off the return fuel line. If the pressure drops, its not the check valve. If the pressure no longer drops, its the check valve. I don't know how hard or risky it is to pinch the stock plastic lines.

 

What kind of pump did you install? Could be faulty check valve or some other leak in the system.

-B

 

it is a walbro 255lph.... car ran with no Fuel Pressure loss ever since installation.

 

I had a problem with my walbro fuel pump, where the check valve failed and caused loss of pressure. Also what kind of hose did you connect the pump?

-B

 

Well I checked my fuel pressure gauge and I found out I bled MAYBE 2psi from when I shut my car off. I am sure everyone already said this would hap'pen, but I told you I would check mine for you so I did.